A combine harvester has at its front end an intake feeder system that cuts the crop from the ground and feeds it to a threshing mechanism. The intake feeder system comprises a header and an elevator that raises the crop to the level of the mouth of the threshing mechanism. Commonly, the header, which takes different forms depending on the type of crop, is wider than the elevator and is provided with two augers arranged one at each side of the header to push the cut crop towards the central elevator. The threshing mechanism separates the grain from the stalks, or straw, and the chaff. The grain is stored in a tank on board the harvester while the straw and the chaff are discharged from the rear end of the harvester.
The threshing is carried out by passing the crop between a rotating cylinder and a surrounding concave. The cylinder has threshing elements on its surface that separate the grain by beating and crushing the crop against the surrounding concave, and the latter has openings through which, the separated grain can fall to be transferred to the storage tank. Depending on the design of the harvester, the cylinder may be disposed longitudinally or transversely but the present invention is primarily concerned with harvesters having longitudinal threshing cylinders.
If rocks or large stones are picked up by the intake feeder system, they can damage the threshing mechanism. One way to prevent such damage is to detect stones by the noise they make as the crop is being advanced towards the mouth of the threshing mechanism and to prevent crop containing a stone from reaching the threshing mechanism. This method is not, however, entirely reliable as small stones buried in the crop may make less noise and may go undetected. Furthermore, the removal of each stone requires an interruption of the harvesting operation, thereby adding to the down time of the combine.
It has also been proposed to pass the crop through a stone or rock separator before it reaches the mouth of the threshing mechanism. An example of a stone separator is described in U.S. Pat. No. 5,882,257.
FIG. 1 of U.S. Pat. No. 5,882,257 is incorporated herein as FIG. 1 of the accompanying drawings. In FIG. 1, a combine harvester 10 has an intake feeder system 12 having a header with a cutter 14 and a reel 16, an elevator 18 and a stone separator 20 arranged between the top of the elevator 18 and the threshing mechanism 22. The stone separator 20 comprises a feed beater 26, in the form of a rotor with projecting paddles, arranged above a rock trap sump 28. The feed beater 26 conveys the crop towards the threshing mechanism 22 while rocks and foreign matter, which are generally heavier and denser than the crop, are impacted and downwardly discharged into the interior of the rock trap sump 28. The rotation of the feed beater 26 propels the rocks and foreign matter downwardly through straw and chaff into the rock trap sump. As a result, the rocks and foreign matter are separated from the crop prior and prevented from reaching the threshing mechanism 22.
It has been found, when a combine harvester intake feeder system is modified to incorporate such a stone separator 20 between the crop elevator 18 and the mouth of the threshing mechanism 22, that clouds of dust and debris are generated above the rotor 26 of the stone separator 20 and it is the aim of the present invention to avoid such clouds as they increase cab pollution and impair visibility.